Method of making piston pins



May 22, 1928. I 1,670,564

c. BREER} METHOD OF MAKING PISTON PINS Original Filed Sept. 28, 19 25 m/III/IIIIIIIIII/IIIIIIIIIIA YIIIIIIIIIIIIIII/IIIIIIIIII/lfl attain;

Patented May 22, 1928.

CARL BREER, OF DETROIT, MICHIGAN, ASSIGNOR TO CHRYSLER CORPORATION,

HIGHLAND PARK, MICHIGAN,

A CORPORATION OF DELAWARE.

METHOD OF MAKING PISTON PINS.

Original application filed September 28, 1925, Serial No. 58,982. Divided and this application filed May 29, 1926. Serial No. 112,601.

This application is a division of my application Serial No. 58,982, filed September 28, 1925.

This invention relates to piston pins and more particularly to the method of making the same.

In the construction of aluminum pistons, considerable. difliculty has been experienced in fitting the piston pins into the plston bosses because otthe difference in the co-- efiicient of expansion of the aluminum piston and bosses over that of the steel pin. It the pin is fitted closely in the bosses, there is a tendency to bind sander extreme cold conditions because of the relatively large contraction of the aluminum with re-. 'spect to the steel.

loosely, there is a tendency to knock under extreme heat conditions due to the relatively large expansion of the aluminum with respect to the steel.

It is the primary object of my invention to provide a method of making a piston pin construction Which will tend tocause the pin to have substantially the same co-efiicient of expansion as the piston and bosses.

lVith the above and other objects in View, my invention consists in the method and process of making the same, as set forth in the specification, claimed in my claims and shown in the accompanying drawings, in which:

Fig. '1 is a longitudinal sectional view of a piston pin constructed in accordance with my invention.

-Fig. 2 is a longitudinal sectional viewillustrating the method of making the same.

Fig. 3 is a sectional view of a piston showing my improved pin mounted therein.

Fig. 4 is a longitudinal sectional view showing a modified method of making the I have shown, a tubular steel shell 5 having a core 6 of aluminum held therein by the end flanges 14. This composite pin is fitted into the bosses 7 of an aluminum piston 8.

For the manufacture of my improved pin I the core 6 is inserted in the shell and is of suflicient length to extend a few thousandths of an inch beyond the ends of the shell. The shell and core are then placed in a die consisting of the members 9 and 10, the opening in the die being slightly larger than the It the pin is fitted in 11. A stationary member 12 is brought to bear against one end of the core 6' and a movable heading punch 13 is positioned opposite the other end of the core. The heading punch 13 is then moved to strike that end of the core which it is opposite so as to upset the core in the shell 5, with the result that the core is compressed within the shell and the shell will be forced outwardly a relatively small amount as indicated by the clearance 11, so as to place it under an expansive strain. In some cases this operation may result in the circumference of the shell being slightly out of round in which event it may be milled to a perfectly round formation and then placed in the bosses 7 of the piston 8. The end flanges 14. may be formed in this operation to definitely locate the core in the shell under all temperature conditions.

It will be apparent that'a piston pin constructed in accordance with the above description will be hi hly responsive in expansion and contract1on to heat and cold. When subjected to heat the aluminum core will follow its natural tendency toexpand the steel shell a greater amount than the shell would normally expand under the same heat. Likewise when subjected to colder temperatures, the core 6 will contract and because of the fact that the shell'5 has been placed under an expansive strain. the shell will follow-the contraction of the core. The obvious result will be that the pin and piston will expand and contract in substantially the same ratio. The clearance 11 permits slight expansion of the shell, when being placed under expansive splrain, without endangering splitting of the s el Itwill be obvious that other combinations of material than steel and aluminum may be utilized in my invention, and I do not wish to be limited to this combination.

As a modification in the manufacture of my improved pin, I have shown in Fig. 4 the pin being disposed in a die, as in Fig. 2..

The core, however, is of slightly less length than the shell and the members 12 and 13 meet the ends of the core within the shell. In this method, the upseting of the core must result in expansion of the shell, inasmuch as.

there is no other escape for the material of the core.

Various other changes may be made in the arrangement, combination and construction of the various parts, without effecting the process used in the manufacture thereof or without departing from the spirit of my invention, and it is my.intention to cover by my claims such changes as may be reasonably included within the scope thereof.

\Vhat I claim is:

1. The process of making an article of manufacture which consists in compressing in a tubular member a core having a higher coefficient of expansion than the tubular member.

2. A process as described in claim 1 wherein said core is compressed to an extent as to place said tubular member under an expansive strain.

3. The process of making an article of manufacture which consists in placing a core in a tubular member and then upsetting the core to compress it in the tubular member.

4. The process of making an article of manufacture which consists in placing in a tubular member a core having a higher coeflicient of expansion than the tubular member and then upsetting the core to place the tubular member under an expansive the core to compress itin the tubular memher and place the tubular member under expansive strain.

6. A process as set forth in claim 5 wherein said tubular members is then trimmed to a true outside round formation.

7. The process of making an article of manufacture which consists in placing an aluminumcore in a steel shell, then upsetting the core to compress it in the shell and place the shell under an expansive strain.

CARL BREER. 

